Printer&#39;s blanket



NOV, 29, 1949 LlLEs T 2,489,791

PRINTERS BLANKET Filed Oct. 16, 1944 jL/EE'IZ 1 271 15 Jean's El 2 [as,..:f.z;z LI -5h? -r 5.2::

Patented Nov. 29,1949

PBINTERS BLANKET Lewis B. Liles, Cuyahoga Falls, and Edgar W. Chapman,Akron, Ohio, assignors to The B. F. Goodrich Company, New York, N. Y., acorporation of New York Application October 18, 1944, Serial No. 558,824

6 Claims. (Cl. 154-545) 1 This invention relates to printers blanketsand is especially useful in the manufacture of blankets for offsetprinting.

Heretofore difllculty has been experienced in providing an offsetblanket which was free from 5 stretch and which at the same timeprovides the proper surface for taking the ink, the proper resiliencerequired in printing, and the uniform flexibility necessary to permitmounting of the blanket about a cylindrical platen. Some of thesediillculties have also been experienced in the manufacture of printersblankets other than the offset type.

In the offset printing process, an offset blanket having an impressionface is drawn tightly about a cylindrical platen and the ends of theblanket are clamped to the platen by metal clamp strips and boltspassing through the clamp strips and the ends of the blanket.Cylindrical printing plates are mounted on a roller so as to haverolling engagement with the face of the blanket to transfer an inkimpression thereto. The material to be printed is passed in sheet formin contact with the inked blanket and lifts the ink from the blanket.The printing process is continuous so that the printing plates contactintermittently with the deposited impression on the blanket and anyshifting of the blanket such as would occur by stretching of the blanketwould result in a smudged impression requiring the press to be stoppedand the blanket cleaned. It has been found that where a press standsidle over night, shifting of the blanket due to stretch usually resultsand requires cleaning and adjustment of the blanket before continuinguse. It has been found necessary to employ a blanket of considerableflexibility so that it accommodates itself perfectly to the supportingcylinder and attempts heretofore to utilize a blanket containingrelatively nonstretchable sheet or woven metallic materials have undulystiffened the blanket and destroyed its flexibility. Blankets reinforcedheretofore with cellulosic fabrics such as cotton or rayon have had theobjection of being unduly stretchable.

The tensioning of the blankets tends to shear the blanket between theattaching apertures therein and the ends of the blanket so that highresistance to shear is required at the'ends of the blanket while at thesame time uniformity of flexibility is required of the blanket fromendto end.

Furthermore, it is desirable for the maker to supply blanket material inlong lengths from which the blankets are cut for use. requiring uni- 2formity of construction throughout a roll of blanket material.

The principal objects of the present invention are to avoid stretch ofthe blanket without interfering with the desirable flexibility andresilience, and to provide resistance to shear about fastening meanswith resistance to stretch.

These and other objects will be apparent from the following descriptionand the accompanying drawings.

Of the drawings,

Fig. 1 shows a perspective view of a portion of an offset blanketconstructed in accordance with and embodying the invention, the blanketbeing broken away in steps to show its construction.

Fig. 2 is a perspective view of a cylindrical press platen having ablanket secured thereabout.

Fig. 3 is a plan view of a portion of a layer of glass fabric.

Referring to the drawings, the numeral l designates a blanket cylinderformed with a cylindrical surface 2 for supporting a blanket 3. Thecylinder is provided with an axial gap 4 into which the ends of theblanket are turned and secured by metal clamp bars 5, 5, and bolts 8, 8passing through the bars and the blanket to tension bars 6, 6, which areadapted to be drawn into the gap by screws 1, I to tension the blanket.The offset blanket 3 has a printing face or impression layer l0 which isof soft vulcanized rubber or other rubber-like material having theproperties of resilience. resistance to the chemical action of ink andsolvents used for removing ink, and also the property of beingattractive to ink or of being wet thereby. Synthetic rubber compositionsand plasticized polymerized vinyl chloride compositions have been foundto have. desirable properties for this purpose, although compositions ofnatural rubber or other rubber-like ma terials may be used for theimpression layer. Material suitable for the impression layer isdescribed and identified for example in Patent No. 2,271,125 to A. E.Juve.

For flexibly supporting the printing face without interfering undulywith its flexibility, a backlug I l of woven cellulosic material such assquare woven cotton or rayon fabric united by rubber or otherrubber-like material is secured to the lower face of the impressionlayer and at least one layer I2 of the backing is formed of glass in theform of filamentary glass elements IZA spun in'to substantiallyinextensibie yarns I2B to provide resistance to stretch both laterallyand iongitudinally of the blanket, and preferably woven to provide afabric. Such glass material is commercialiy known as "Fiber glass" andis illustrated in Fig. 3. In the backing shown, a layer ll ofprestretched square woven fabric of cotton or rayon forms the foundationlayer and a layer ll of similar material forms the top layer of thebacking and is bonded to the impression layer. The layer I2 of fiberglass is located between the layers 13 and I4 and is separated therefromand bonded thereto by thin layers l5, l6 of rubber or other rubber-likematerial which unites the fabric layers to each other through the meshesof the fiber glass and provides a cushioning of the fabric layer whichpermits bending of the blanket, the rubber-like material permittinglongitudinal creep of the layers with respect to each other duringbending. While rubber-like materials do not ordinarily adhere readily tomaterials such as glass, it has been discovered by us that where theglass is of filaments forming spun yarns and woven as a fabric, theadhering of the rubber-like material to the fabric is amply sufficientfor the purpose and while glass is ordinarily considered a brittlematerial, nevertheless in the form of woven filamentary glass elementsit is free from brittleness and is highly flexible in all directionswhile providing great resistance to stretch. All the woven layers havetheir warp and filler elements extending respectively lengthwise andcrosswise of the blanket. The square woven fabric at each side of thefiber glass layer protects it from accidental injury and prevents shearof the blanket about bolt holes while the fiber glass layer providesgreat resistance to stretch of the blanket. All of the layers of theblanket are adhered to each other and united by vulcanization of therubber-like material, the layers being assembled and united underpressure by application of heat.

In use, the blanket is secured about the cylinder l of the press bybolts 8, B secured through openings 20 punched at intervals through theends of the blanket to receive the bolts 8. The use of cotton or otherfabric at each face of the layer of fiber glass reinforces the fiberglass against shearing and separating between the bolt holes and themargin of the blanket adjacent thereto.

While only one layer of fiber glass is shown in the illustrativeembodiment, one or more such layers may be employed, preferably with allof the layers of fiber glass located between piles of fabric.

Variations may be made without departing from the scope of the inventionas it is defined by the following claims.

We claim:

1. A printers blanket uniform in flexibility and highlystretch-resistant in a direction of the blanket for resistingobjectionable deformation in the use thereof, said blanket comprising aresilient impression layer of ink-retainable material having thephysical properties of soft, vulcanized rubber resistant to the chemicalaction of ink materials and solvents, and a flexible backing integralwith said impression layer, said backing comprising stretch-resistantmaterial including glass in filamentary form extending along the blanketin said direction thereof.

2. A printers blanket uniform in flexibility and highlystretch-resistant in a direction of the blanket for resistingobjectionable deformation in the use thereof, said blanket comprising aresilient impression layer of ink-retainable material having thephysical properties of soft, vulcanized rubber resistant to the chemicalaction of ink ma- 4 terials and solvents, and a flexible backingintegral with said impression layer, said backing comprisingstretch-resistant material including glass in filamentary elementstwisted together to provide tension members extending along the blanketin said direction thereof.

3. A printer's blanket uniform in flexibility and highlystretch-resistant in a direction of the blanket for resistingobjectionable deformation in the use thereof, said blanket comprising aresilient impression layer of ink-retainable material having thephysical properties of soft, vulcanized rubber resistant to the chemicalaction of ink materials and solvents, and a flexible backing integralwith said impression layer, said backing comprising stretch-resistantmaterial including glass in filamentary elements twisted together asyarns and woven in fabric form to provide tension members extendingalong the blanket in said direction thereof.

4. A printers blanket uniform in flexibility and highlystretch-resistant in a direction of the blanket for resistingobjectionable deformation in the use thereof, said blanket comprising aresilient impression layer of ink-retainable material having thephysical properties of soft, vulcanized rubber resistant to the chemicalaction of ink materials and solvents, and a flexible backing integralwith said impression layer, said backing comprising stretch-resistantmaterial including glass in filamentary form extending along the theblanket in said direction thereof, and a layer of woven cellulosicmaterial adjaceent said stretch-resistant material and adhered theretoproviding resistance of the blanket to shearing stress.

5. A printers blanket uniform in flexibility and highlystretch-resistant in a direction of the blanket for resistingobjectionable deformation in the use thereof, said blanket comprising aresilient impression layer of ink-retainable material having thephysical properties of soft, vulcanized rubber resistant to the chemicalaction of ink materials and solvents, and a flexible backing integralwith said impression layer, said backing comprising stretch-resistantmaterial including glass in filamentary form extending along the blanketin said direction thereof and layers of woven cellulosic material aboveand below said stretch-resistant material and adhered thereto providingresistance of the blanket to shearing stress.

6. A printers blanket uniform in flexibility and highlystretch-resistant in a direction of the blanket for resistingobjectionable deformation in the use thereof, said blanket comprising aresilient impression layer of ink-retainable material having thephysical properties of soft, vulcanized rubber resistant to the chemicalaction of ink materials and solvents, and a flexible backing integralwith said impression layer, said backing comprising stretch-resistantmaterial including glass in filamentary form extending along the blanketin said direction thereof and layers of woven cellulosic material aboveand below said stretch-resistant material and adhered thereto providingresistance of the blanket to shearing stress, said cellulosic materialcomprising square woven cotton fabric secured to said stretch-resistantmaterial by rubber-like material.

LEWIS R. LILES. EDGAR W. CHAPMAN.

(References on following page) 5 m Number R ENCES CITED 2,133J83 Thefollowing references are of record in the 2,135,057 file of this patent:2,184,326 UNITED sums PATENTS 6 2,271,125

Number Name Date 668,919 Hill et a1. Feb. 26, 1901 Number 1,096,893Ellis May 19, 1914 454,452

6 Name Date Baird et a1 Oct. 11, 1938 Slayten et a1 Nov. 1, 1938 ThomasDec. 26, 1939 Juve Jan. 2'7, 1942 FOREIGN PATENTS Country Date GreatBritain Oct. 1, 1936

